PURPOSE: To economize the protection of information, by transmitting a specific bit pattern for a prescribed time as a section of control information in an information processor such as telephone exchange for discriminating surely the control information.
CONSTITUTION: The information inputted from a terminal 3 is latched to flip- flops 4, 5 at the interval an integer numbers a reception synchronizing clock by a timer 2, the content is compared at an exclusive OR circuit 6, and the content of the flip-flop 5 is compared with a specific bit at an exclusive OR circuit 7 at the same time. When each comparison is coincident at the same time, a counter 8 is counted up and when the count value reaches a prescribed value, the result is set to a flip-flop 9, it is recognized as the specific pattern, i.e., the section between sets of control information, and a signal line 10 goes to 1. When the comparison of the circuit 6 is coincident and the comparison of the circuit 7 is not coincident, a counter 11 is counted up only when the signal line 10 is at 1 level, and the control information is recognized when the counter reaches a prescribed value.
KITANO HIROSHI
UEDA HISAO
IWAMOTO YOSHIHARU
AWAJI TOSHIO
NIPPON TELEGRAPH & TELEPHONE
OKI ELECTRIC IND CO LTD
HITACHI LTD
FUJITSU LTD
| JPS56116349A | 1981-09-12 | |||
| JPS5162707U | 1976-05-18 | |||
| JPS5177106A | 1976-07-03 |